Crystal field engineering via Sr modulation for tunable broadband emission and enhanced afterglow in Ca1-xSrxZnOS: Cu, Y phosphors

CaZnOS is regarded as an excellent phosphor host with relatively favorable doping sites. However, CaZnOS-based long-persistent luminescence (LPL) materials still encounter challenges such as a narrow emission color range and short persistent luminescence lifetime. In this work, we modulated the emission band and LPL properties of a series of Ca 1-x Sr x ZnOS:0.1%Cu,1%Y phosphors through crystal field engineering by controlling the Sr/Ca ratio. The emission peak of the phosphor series was successfully tuned over 524–681 nm (from blue-green to orange-yellow), accompanied by a remarkable enhancement in both emission intensity and afterglow duration as x increases from 0 to 0.9. Moreover, the anomalous luminescence behavior of the SrZnOS:0.1%Cu,1%Y sample implies the crucial role of the Sr/Ca substitution-induced lattice distortion for tailoring the luminescence properties. Thermoluminescence (TL) spectra reveal that the persistent luminescence properties of these phosphors are closely correlated with their trap depth controlled by the Sr substitution ratio. This work provides an important reference for the composition design and development of high-performance LPL phosphors.